A prophy angle is a dental appliance employed by a dentist or dental hygienist in a dental treatment to remove the plaque and polish the surface of the dentin of teeth. A prophy angle includes a prophy cup that is secured to the angle and is rotated by a drive mechanism, typically a gear drive. The prophy cup is shaped to retain a desired amount of prophy paste, which is used to polish and clean a patient's teeth.
In order to rotate a prophy cup to perform the teeth cleaning and polishing task, a dental prophy angle includes a driving mechanism that is typically implemented with a gear connection between a driving gear shaft and a driven gear rotor with a right angle. The driving rotor is rotated by a dental handpiece with a speed of about 2,000 to 5,000 rpm, then the rotation is transferred to the driven rotor by the gearing mechanism resulting in rotating the attached prophy cup at a right angle.
However, since the prophy angle includes the moving parts connected by driving gears while the gear connections and the prophy cup are continuously operated with high speed rotation, the long term reliability and consistent performance of the gear connection and the rotational prophy cup become a technical challenge. Poor long-term reliability often becomes a problem, particularly for the components made of plastic. The plastic components may be implemented either as moving parts or as part of the gear connections between the moving parts and these plastic components often cracks or break off when subject to tearing forces if these the moving parts or the gear connections are not tightly engaged. In order to improve the reliability by reducing the material wear and degradation under constant use and to eliminate potential weak links, many patented inventions have been disclosed. These disclosures provide new gear material, gear shape, gear position and novel lubrications. These previous patents include U.S. Pat. Nos. 6,203,322, 5,964,590, 5,749,728, 5,730,595, 5,645,426, 5,120,220, and 5,040,978. However, in the present market, many of the prophy angle products still exhibit operating life problem because of the insecure gearing connection, which leads to unreliable performance and causes inconvenience for dentists and hygienists
Therefore, a need still exists in the art of designing, component manufacturing and assembling the prophy angles to provide new and improved configuration implemented with better engagement contacts between the moving components to enable a more secure retaining of the driving shaft and driven rotor to assure reliable and high performance operations of a prophy angle.